Synthetic zeolite contact masses and method for making the same



United States Patent "ice 3,367,886 SYNTHETLTC ZEDLHTE CONTACT MASSESAND METHUD FER MAKING THE SAME Walter L. Haden, In, Metuchen, and FrankJ. Dzierzanowski, Somerset, Null, assignors, by mcsne assignments, toEngelliard Minerals & Chemicals Corporation, Menlo Park, Edison, N.J., acorporation of Delaware No Drawing. Continuation-impart of applicationSer. No. 343,952, Feb. H, 1964. This application Feb. 16, 1966, Ser. No.527,744

18 Claims. (Cl. 252-455) ABSTRACT 0F THE DISCLOSURE Zeolitic molecularsieve-kaolin clay composites are provided by a process whereby thebonding steps and crystallization steps are integrated as a result ofcrystallizing the zeolitic molecular sieve from sources of alkali metaloxide, aluminum oxide, and silicon dioxide and water in the presence ofraw (hydrated) crystalline kaolin clay while said sources and said rawkaolin clay are intimately mixed together and in the form of particlesof the size and shape desired in the active contact masses. In carryingout the process, the formed particles are subjected to hydrothermaltreatment without dehydration, whereby the zeolite is crystallized insitu in the presence of the raw clay which, for the most part, does notenter into the reaction. The reacted particles, which possessconsiderable mechanical strength, comprise a self-bonded mixture ofkaolin clay crystals and synthetic zeolitic crystals. The particles areactivated by thermal treatment which dehydrates both the zeolite and theclay crystals. Before the activation step, the particles may beionexchanged with cations that will impart specific desired propertiesto the particles.

In a preferred form of the invention, a high silica-toalumina ratio formof type Y zeolite is crystallized in situ in the presence of the kaolinclay and the particulate reaction mixture includes sodium hydroxidesolution and three different forms of kaolin clay. Two of these claymaterials are dehydrated calcined noncrystalline products, one(metakaolin) having been obtained by a relatively mild calcinationtreatment and the other having been obtained by a more severe treatment.The third clay is the raw crystalline kaolin clay.

This application is a continuation-in-part of our c0- pendingapplications Serial No. 343,952, filed February 11, 1964 and nowabandoned, Serial No. 389,188, filed August 12, 1964 and Serial No.446,730, filed April 8, 1965.

The present invention is concerned with composite synthetic zeolitecontact masses and their preparation from naturally occurring clay. Theinvention is especially directed to composite cracking catalysts.

Noteworthy advances in the fields of adsorption and catalysis haveresulted from the synthesis of unique crystalline aluminosilicatezeolites known as molecular sieves. Zeolites of this type retain theirstructure when at least part of their water of composition is removed,resulting in silicates which possess internal adsorptive areasaccessible through openings or pores of definite dimensions which arecharacteristic of the specific dehydrated zeolite.

Synthetic molecular sieve zeolites are prepared commercially byprecipitation from dilute aqueous reaction mixtures containing highpurity sources of oxides of sodium, aluminum and silicon in proportionsselected to produce the desired zeolitic molecular sieve. For example,

3,367,886 Patented Feb. 6, 1968 to prepare the molecular sieve typezeolite known as zeolite Y the reactants described in U.S. 3,130,007 toBreck can be used. A similar zeolite known as zeolite X can be producedwith reactants described in U.S. 2,882,- 244 to Milton.

For virtually all of their industrial uses, synthetic crystallinemolecular sieves must be bonded into uniform particles of desired sizeand shape, such as cylindrical pellets or microspheres. The binder thatis used must be such that the valuable properties of the molecular sieveare retained. For uses such as hydrocarbon conversion catalysts,relatively large pore diameter zeolites, such as zeolite X and Y, areused in the form of shaped particles which must possess considerablemechanical strength and thermal stability, especially steam stability.The use of clays as binders for the zeolite crystals has been suggested.To produce such bonded composites, the zeolite is first obtained as afine crystalline precipitate from dilute reactants. The precipitate isthen mixed with water and plastic clay, shaped into particles and heatedto set the bond and dehydrate the clay. Reference is made to U.S.2,973,327 to Mitchell et al. and U.S. 3,140,253 to Plank et al.Clay-zeolite composites of this type are expensive to produce, primarilybecause of the high cost of the reactants required to crystallize thezeolite and the requirement for a separate bonding step. Moreover, theclay bonded composites leave much to be desired in the way of hardness,especially resistance to attrition. This is especially true ofclay-bonded composites suitable for use as cracking catalysts.

An object of this invention is to provide zeolitic molecular sievecomposites by a process whereby the sieve is crystallized in situ in thepresence of clay in theform of particles of the size and shape desiredin the zeolitic molecular sieve composites.

Another object is to provide a process for making particulate molecularsieve composites by a process whereby bonding and crystallization stepsare integrated and the need to crystallize the zeolite and thereafterbond the zeolite is obviated.

Another object is to produce molecular sieve composites fromcomparatively inexpensive mineral ingredients.

Still another object is to produce composites of clay and zeoliticmolecular sieves which, when heat activated, are substantially harderand more resistant to attrition than products of generally similarcomposition but which are made by binding previously formed precipitatedzeolite particles with water and plastic clay.

A further object is to produce a molecular sieve in direct contact witha clay diluent which facilitates agglomeration of the molecular sieveand which aids in controlling mass temperature during the reactionforming the molecular sieve.

Another object is the provision of novel methods for converting kaolinclay into cracking catalysts which are markedly more selective thanpresent-day commercial acid-activated clay cracking catalysts even atexceptionally high conversion rates and which have desirable hardness aswell as outstanding steam stability.

Another object is to provide molecular sieve composites which possessoutstanding stability in the presence of liquid water.

Other objects and features of this invention will be 7 when the otheringredients are reacted and crystallized.

In carrying out the present invention, raw (fully hydrated oruncalcined) kaolin clay is mixed with an aqueous slurry containingreactants (sources of oxides of silicon, aluminum and alkali metal)capable of reacting to produce a synthetic crystalline zeoliticmolecular sieve when subjected to hydrothermal treatment withoutdehydration at about 70 F. to 100 F. and then crystallized underautogenous pressure at 150 F. to 225 F. in the absence of the raw clay.Sufiicient raw kaolin (a crystalline aluminum silicate of theapproximate formula Al O .2SiO .2H O) is employed to form a coherentmass with said aqueous reactants. In other words, the raw clay ispresent in amount sutficient to thicken the reaction mixture, and areaction mixture which would have the consistency of a fluid slurry inthe absence of raw kaolin clay forms coherent reaction particles whenthe raw clay is mixed therewith. Also included in the mixture is a smallamount of a source of alkali metal oxide in addition to the alkali metaloxide required to crystallize the zeolitic molecular sieve in theabsence of the added hydrated kaolin clay. This excess of alkali metaloxide is needed to crystallize the zeolite in the presence of the rawclay. The mixture of ingredients is then formed into particles, whichcan be of the shape and substantially of the size desired in thefinished contact masses. The particles are subjected to hydrothermaltreatment without dehydration until reaction occurs and a hydratedalkali metal aluminosilicate molecular sieve crystallizes in situ in thepresence of the raw clay. X-ray diffraction patterns of the product atthis point of the process indicate the resulting base material containstwo crystalline components, namely, a crystalline zeolitic molecularsieve (hydrated alkali metal oxide form) and kaolin clay crystals. Thespecies of zeolitic molecular sieve that is crystallized usually hassubstantially the same characteristic X-ray diffraction lines that thereactants would produce in the absence of the raw clay and extra alkalimetal oxide. Present experience indicates that some amorphous material,i.e., material which does not exhibit strong characteristic X-raydiffraction lines, is also present.

The bond between the constituents of the reacted and crystallizedparticles is strengthened when the base material is activated by heattreatment before or during use. Such heat treatment dehydrates thezeolite and the kaolin clay at least partially. The crystallinity of theclay is destroyed or reduced during the heat treatment. Thecrystallinity of the zeolite may also be reduced during such treatment.Prior to the heat treatment to strengthen the bond and activate thezeolite, it may be desirable to ionexchange the zeolite with cationsthat will impart specific desired properties to the product. Forexample, to make a cracking catalyst, the ingredients of the reactionmixture are selected to crystallize a relatively large pore diameterzeolitic molecular sieve, eg, sodium zeolite Y. The resulting basematerial can then be subjected to base-exchange with ammonium ions andactivated thermally.

In carrying out the process of the present invention, the raw clayfacilitates particle formation since it permits shaped particles to beformed directly from reaction mixtures not amenable to shaping byconventional means in the absence of the raw clay. Further, the raw clayfunctions as a heat sink during the exothermic reaction leading tozeolite formation and thereby minimizes the possibility of such reactiongetting out of control. The presence of the clay in the composites,especially the heatactivated composites, provides desirable stability,especially steam stability, to the composites.

Products of this invention possess remarkable hardness. These particlesare significantly harder than particles of similar composition thatwould be obtained by following the prior art practice of precipitatingzeolite as finely divided crystals and then binding the crystals byadding water and raw plastic clay. Composites of especially noteworthyhardness are obtained when carrying out this invention using calcinedclay(s) with sodium hydroxide solution as reactants to form thecrystalline zeolite.

However, in order to obtain a strongly bonded mixture of zeoliticmolecular sieve and dehydrated clay by reaction in situ in the presenceof raw kaolin, the zeolite must actually undergo crystallization in thepresence of the raw clay crystals. Mere reaction of calcined kaolin andcaustic solution in the presence of the raw clay without actualcrystallization of the zeolite results in a relatively Weak bond. Whilethe zeolite must be crystallized in the presence of the raw clay, thecrystalline state of the zeolite may be subsequently destroyed orreduced without substantial impairment of strength and, in some cases,without substantial impairment of the activity of the composite.

It is not presently understood why the process of the invention leads tothe formation of composites of such remarkable mechanical strength. Infact, the result is surprising when viewed in light of the fact that theheat activated composites obtained by crystallizing zeolitic molecularsieves in the presence of kaolin clay crystals are also much harder thansimilarly heat-treated particles of the raw clay per se. Thus, thezeolite ingredient contributes to bond strength when it is crystallizedfrom concentrated reactants in the presence of the clay and it impartshardness to the clay that the clay would not possess in the absence ofthe zeolite.

The specific molecular sieve component of the product can be varied byvariation in reactants and/or reaction conditions. The zeoliticmolecular sieve is crystallized in alkali-metal, usually sodium, form.For example, zeolitic molecular sieves such as zeolite A, X and Y, whichare crystallized in sodium form, can be obtained by using sodiumhydroxide with suitable sources of reactive alumina and silica and rawclay. Type L zeolite is obtained with a mixture of potassium hydroxide,sodium hydroxide, suitable sources of reactive silica and alumina, andraw kaolin clay. As is known in the art, the alkali-metal form of thezeolite can be exchanged with other cations to form molecular sieves ofdesired properties. This invention thus encompasses the preparation ofcomposites containing a molecular sieve component of the formula In theformula, M is a cation (e.g., a metal in groups I, II and III of theperiodic table, transition metals of the periodic table, hydrogen,ammonium or mixtures of the aforementioned), v is the valence of M, n isa number having a value of at least 2 and Y is a variable depending uponthe number of mols of Si0 and the identity of M. The species ofmolecular sieve in the product can be identified by standard X-raydiffraction technique. The quantity of crystalline sieve can also beestimated by means of X-ray diffraction patterns.

In accordance with a preferred embodiment of this invention, hard stablecatalyst agglomerates are produced from a mixture of sodium hydroxidesolution and three forms of clay; namely (1) metakaolin, (2) kaolinwhich has been calcined at a temperature and for a time such that theclay undergoes the characteristic kaolin exotherm at about 1800 F. afterdehydration is substantially complete and (3) uncalcined (fullyhydrated) kaolin clay. In other words, in accordance with this form ofthe invention, the reaction masses are obtained from a mixture ofuncalcined fully hydrated kaolin clay and two distinctly differentanhydrous forms of kaolin clay. The reacted agglomerates contain acrystalline phase having substantially the X-ray diffraction pattern ofsodium zeolite Y as described in U.S. 3,130,007 to Breck or zeolite X asdescribed in U.S. 2,882,244 to Milton. The resulting composite basematerial is base-exchanged to remove alkali cations and then calcined toactivate the composite. A

characteristic of such catalyst composites is that they are remarkablyselective even at exceptionally high conversion levels and possessremarkable steam stability. Another noteworthy feature of the catalystsis that they operate with the desirable selectivity characteristics ofthe fresh catalyst even when the catalytic activity decreases duringservice. Thus, the catalysts do not acquire the cracking characteristicsof the dehydrated kaolin clay diluent. This, of course, is not true ofprior art composite catalysts that contain catalytically active gelmatrices. Another characteristic of catalysts of the invention is thatthey can be produced as very hard shaped masses. The calcined claymixture appears to contain some nonreactive constituents which, it isbelieved, contribute to the remarkable hardness of catalyst compositesobtained with such ingredients. Typically, the catalysts have bulkdensities within the range of 0.80 to 1.00 g./Cc.

Following is a more detailed description of reactants useful in carryingout our invention, following which a description of reaction conditionsis given.

REACTANTS (l) The source of soluble alkali metal oxide Sodium hydroxidecan be used as the source of all of the alkali metal oxide. In producingcertain molecular sieves it may be necessary to employ potassiumhydroxide, lithium hydroxide, mixtures thereof and mixtures with sodiumhydroxide. Quaternary ammonium base can be used. It is also within thescope of the invention to employ soluble alkali metal silicate as asource of soluble alkali metal oxide. The meta-silicate or thedisilicate can be used. Mixtures of alkali metal hydroxide and alkalimetal silicate can be employed.

The source of alkali metal oxide is used in the form of an aqueoussolution. Employing sodium hydroxide, aqueous solutions of percent to 45percent NaOH concentration (weight basis) are used. Solutions of 10percent to 30 percent sodium hydroxide concentration are especiallyuseful in producing catalyst composites by reaction with calcined kaolinin the presence of raw clay. At sodium hydroxide concentrationsappreciably below 10 percent, the desired zeolite may not form in thepresence of raw kaolin clay diluent since the raw clay may inhibitformation of the desired zeolite under these circumstances. At sodiumhydroxide concentrations appreciably above 35 percent there may beinsufficient liquid phase to form coherent particles unless a largerquantity of sodium oxide is employed. The use of large quantities ofsodium oxide may, however, prevent the formation of highsilica-to-alumina ratio zeolites which are generally preferred forcracking catalyst preparations. Especially good catalysts have beenprepared from mixtures of calcined kaolin clay, aqueous-solutions of 12percent to 18 percent sodium hydroxide concentration and raw kaolinclay.

Using sources of alkali metal oxide other than sodium hydroxide,solutions of corresponding metal oxide concentrations are suggested.

A freshly prepared concentrated aqueous solution of sodium aluminate canbe employed as a source of some of the sodium oxide, especially when ahighly absorptive, particulate source of alkali-reactive silica, such assilica gel or diatomaceous earth, is used as the source of silica.

(2) Sources of reactive silica and alumina The sources of reactivesilica and alumina should include a substantial amount of finely-dividedabsorptive material, preferably finely divided mineral matter. Examplesof finely divided absorptive mineral matter which are sources of aluminaand/or silica are calcined kaolin clay, bauxite, diatomaceous earth andtripoli. Also useful are amorphous alkali-reactive silica, such assilica gel and the silica residue obtained by removing cations otherthan silica from a silicate mineral having a continuous network, e.g., asilica residue obtained by acid leaching of a clay. Preferably, finelydivided calcined kaolin clay that has been calcined to a L.O.I. below 1percent is employed as a reactant to produce the zeolite. The termL.O.I. refers to loss on ignition and is determined at 1800 F.

C-alcined clays that are especially useful are supplied commercially asfinely divided white pigments. These clays are available in two grades.One is a minus 325 mesh (Tyler) product of very high whiteness ascompared with the whiteness of the raw kaolin clay from which it isobtained. Such calcined clay usually has a GE. brightness of at least 90percent. This material, exemplified by the material supplied under thetrade name Satintone #1, is prepared by calcining minus 325 meshdegritted kaolin clay to an L.O.I. below 1 percent at a temperature ofabout 1600" F. to 2000 F. and for a time such that the clay completes(passes through) the characteristic exotherm at about 1800" F. afterdehydration is substantially complete. The high temperature calcinedclay is obtained at calcination temperatures below which substantialcrystallization of high temperature phases, such as cristobalite and/ormullite takes place. The use of the high temperature calcined claypigment leads to the crystallization of zeolitic molecular sieves ofrelatively large pore diameter and high silica-to-alumina ratio, e.g.,type X and Y zeolites, and is especially desirable for producingcracking catalyst composites. The other type of commercial calcinedkaolin clay is a minus 325 mesh dehydrated amorphous aluminum silicateobtained by calcining clay to an L.O.l. below 1 percent at a temperature and for a time such that the clay has not undergone the exothermicreaction at about 1800" F. Such clay, exemplified by Satintone #2, isfrequently referred to as metakaolin and usually has a lower brightness(typically 83 percent to 85 percent) than the clay from which it wasobtained. Metakaolin can be obtained by calcining kaolin clay at atemperature within the range of about 1000 F. to about 1550" F. untilthe 1.0.1. of the clay is below 1 percent. It is also within the scopeof this invention to employ partially dehydrated clay which has beencalcined under conditions that produce a mixture of hydrated clay andmetakaolin. To prepare a cracking catalyst from such a mixture andsodium hydroxide solution the reaction masses should also containcalcined clay that has passed through the exotherm during thecalcination.

Calcined kaolins containing the usual impurities can be used. Typicallythe calcined clays may contain 1 percent to 2 percent TiO small amountsof fen'uginous matter and quartz. Metakaolin can be distinguished fromother forms of anhydrous kaolin clay by the fact that it undergoes thecharacteristic exotherm when heated to about 1800 F. for a suflicienttime. The presence of the exotherm can be determined by a differentialthermal analysis, using the technique described in Grims ClayMineralogy, page 203, published by McGraw-Hill Book Company, Inc.(1953).

Metakaolin is a reactive source of alumina and silica. When mixed withconcentrated sodium hydroxide solution and subjected to hydrothermaltreatment without de hydration, as described in US. 3,065,054- to Hadenet al., sodium zeolite A is crystallized. In carrying out an embodimentof the process of the invention, raw kaolin clay is mixed withrnetakaolin and sodium hydroxide of suitable concentration to producecomposites including zeolite A. When metakaolin is reacted with sodiumsilicate in the presence of raw kaolin clay, as shown in theaccompanying examples, composites containing sodium zeolite X or Y areobtained. When the metakaolin is employed with sodium hydroxide solutionand a substantial amount of kaolin that has been calcined above theexotherm, the formation of sodium zeolite X or Y is favored. Compositescontaining a high silica-to-alumina ratio form ssszsss of zeolite Y canbe obtained from these components by employing a large percentage ofhigh temperature calcined clay with metakaolin, sodium hydroxidesolution and raw kaolin clay. While high silicato-alumina ratio zeolitescan be crystallized in the presence of raw kaolin clay by reacting thehigh temperature calcined clay and sodium hydroxide solution withoutmetakaolin, the quantity of zeolite crystallized in the presence of rawkaolin is generally improved to a substantial extent by employing amixture of the calcined clays with the caustic and raw kaolin. Thecalcined clays can be mixtures of two different types of clays'obtainedin separate calcination operations or the mixture can be obtained in asingle calcination operation.

It is reasonable to expect that a freshly prepared aqueous solution ofsodium aluminate can be used as the sole or partial source of reactivealumina, especially when such material is used in conjunction with aparticulate adsorptive source of high purity silica, such as silica gelor tripoli. However, the use of a mineral source of reactive alumina, esccially calcined kaolin clay, is preferred.

(3) Uncaicz'ned clay A clay consisting predominantly of kaolinite (orequivalent dickite, anauxite, nacr-ite or halloysite) is used. Bentoniteclay and attapulgite clay are not suitable. A kaolinite having goodextrusion properties should be used when particle formation is to beaccomplished by such means. Excellent results have been realized withwaterwashed white kaolin clays from Georgia. The uncalcined clay that isused possesses the fundamental characteristics of the clay as mined andis therefore usually referred to as raw kaolin. Such material may haveundergone purification by any one of the following: degritting,fractionation, bleaching, flotation, or other procedure for removingimpurities.

PROPORTION OF REACTANTS The composition of our reaction masses will, ofcourse, vary with the particular sieve-type zeolite that is desired andwith the desired dilution of such sieve in the end product.

The reaction masses may be considered to contain two groups ofingredients. The ingredients that would form a zeolite in the absence ofraw kaolin may be considered to constitute one group and include alkalimetal oxide, reactive silica, reactive alumina and water. Raw kaolin anda supplemental quantity of alkali metal oxide constitute the othergroup.

The first group is selected to provide a mix which will crystallizehydrothermally to form a zeoliti molecular sieve of desired species inthe absence of raw clay. The raw kaolin is employed in amount to thickenthe other ingredients. The quantity of alkali metal oxide in the secondgroup of ingredients will vary somewhat with raw clay of differentorigin and particle size. Typically, this amount is within the range of0.05 mols to 0.50 mols alkali metal oxide per mol raw clay (Al O .2SiO.2H O). For example, a slurry of suitable calcined clays and sodiumhydroxide solution of 12 percent to 18 percent concentration can formhigh purity sodium zeolite Y of about 4 silica to alumina ratio (asdetermined by X-ray) using 0.40 to 0.65 mols Na O per mol A1 in thecalcined clays. When these materials are reacted in the presence of atypical raw clay, in accordance with the present invention, about 0.45to 0.75 mols of Na O per mol calcined clay would be used. By way offurther example, type A zeolite can be crystallized in massive form fromingredients of the first group using proportions of 1 mol metakaolin anda sodium hydroxide solution of 30 percent to 55 percent concentration inamount to provide 1 mol Na O per mol of metakaolin. Reference is made toUS. 3,065,054 to Walter L. Haden, Jr. and Frank Is. Dzierzanowski.Similarly, type A Zeolite can be crystallized in massive form from aslurry of particulate amorphous silica, such as silica gel, and aconcentrated freshly prepared aqueous solution of sodium aluminate, asdescribed in US. 3,094,383 to Haden et al. To make type A adsorbentcomposites of the invention from the metakaolin and a concentratedsodium hydroxide solution, the reaction masses can be formulated asfollows:

ingredient: Quantity (1) Kaolin dehydrated substantially completely at atemperature below the kaolin exotherm 1 mol (calculated as Al O .2SiO

(2) Uncalcined kaolin clay to mol (calculated (3) NaOH as aqueoussolution, preferably of 30 percent to 45 percent concentration To supply1 mol N2 0 plus 0.05 to 0.80 mol Na o per mol (2) and of a concentrationsufficient to thicken (l) and (2) Hydrothermal treatment of theingredients enumerated above results in the formation of compositescomposed of a major amount of molecular sieve having substantially theX-ray diffraction of zeolite A, as described in US. 2,841,471 to Sensel.The composites also contain unreacted crystalline kaolin. When heatactivated, the particles have less tendency to disintegrate in waterthan self-bonded particles of similar size and shape made without rawclay present during reaction.

In producing catalysts from sodium silicate, metakaolin and uncalcinedkaolin, the following proportions are suggested:

Ingredient: Quantity (1) Metakaolin 1 mol (calculated as Al O .2SiO (2)Uncalcined kaolin clay 1 to 30 mols (calculated (3) Sodium silicate asaqueous solution To supply 1 mol Na O per mol (l) and 0.05 to 0.80 molNa O per mol (2); and to supply 0.5 to 3.5 mols SiO Compositescontaining synthetic faujasite (zeolite X or zeolite Y) can be obtainedfrom mixtures of aqueous sodium hydroxide solution, calcined kaolin clayand uncalcined kaolin clay having compositions falling within thefollowing range:

Parts by weight Uncalcined kaolin clay Substantially anhydrous amorphouscalcined kaolin clay Aqueous sodium hydroxide of 10 percent to 30percent concentration, preferably 10 percent to 20 percent concentrationto make a plastic mixture with the above and to supply 0.45 to 1.20 molsNa O per mol A1 0 in the calcined kaolin clay For every 100 parts byweight of total calcined kaolin clay in the composition givenimmediately above, the proportion of metakaolin to the high temperaturedehydrated kaolin clay falls within the range of O to 100 parts byweight of metakaolin to 100 to 0 parts by weight of high temperaturecalcined clay. When all of the calcined kaolin is in the form ofmetakaolin, the reaction mass must be aged for extremely long periods atroom temperature in order to crystallize synthetic faujasite. Asmentioned, above, when all of the calcined clay is in the form of thehigh temperature calcined clay, less crystallization results for a givenaging and crystallization period than when mixtures of the calcinedkaolin clays are used.

Particularly good results have been realized when the sodium hydroxideconcentration in the reaction mixture has been selected to provideslightly in excess of /2 mol Na O per mol total A1 in the calcinedclays. The use of about 0.50 to 0.75 mol Na O per mol A1 0 in thecalcined clays is recommended. When less than about /2 mol Na O is used,the masses do not crystallize as readily as when more Na O is present.When excessive Na O is present, the nature of the zeolite is affectedand this in turn adversely affects the catalytic properties of thefinished catalyst.

In carrying out the preferred form of our invention wherein sodiumhydroxide solution is employed with a mixture of calcined koalin claysand raw kaolin clay to produce a composite including syntheticfaujasite, suitable reactants are as follows:

Ingredient: Quantity (1) Metakaolin 1 mol (calculated as Al O .2SiO-)(2) Kaolin clay dehydrated substantially completely and calcined at atemperature sufiicient to complete (pass through) the kaolin exotherm /2to 10 mols, most preferably 3 to 7 mols (calculated as Al O .ZSiO (3)Uncalcined kaolin clay At least combined amounts of (1) and (2) (on aweight basis) (4) Aqueous NaOH solution of 10 percent to 30 percentconcentration, preferably 10 percent to 20 percent concentration Tosupply 0.45 to 1.2

mols Na O, preferably 0.50 to 0.75 mols Na O per mol A1 0 in combinedamounts of (l) and (2) The ratio of metakaolin to the high temperaturecalcined clay in the reaction mixture affects the nature of the zeoliteand the properties of the product, especially the thermal stability ofthe product. Within the preferred limits of 3 to 7 mols high temperaturecalcined clay to 1 mol metakaolin and 0.50 to 0.75 mol Na O per mol A1 0in the calcined clays, high silica-to-alumina ratio (by X- ray) sodiumzeolite Y is crystallized and highly active and selective catalysts areobtained. These catalysts have excellent steam stability at temperaturesof 1350 F. and above. Especially preferred is the use of about 5 to 7mols of the high temperature calcined clay to 1 mol of metakaolin. Theuse of these proportions results in catalysts that are stable in thepresence of steam at temperatures as high as 1550" F. or 1600 F. Usingmol ratios of high temperature calcined clay to metak-aolin appreciablyless than 3 to 1, the catalysts may not be as stable when steamed attemperatures above 1350 F. as catalysts obtained with a higherproportion of the high temperature calcined kaolin clay. On the otherhand, when using ratios of high temperature calcined kaolin clay tometakaolin appreciably higher than 7 to 1, less crystallization mayresult than when employing the preferred ratio of calcined clays.

A process for synthesizing faujasite zeolites from a mixture ofmetakaolin, high temperature calcined kaolin clay and sodium hydroxidesolution is claimed in our copending application Serial No. 347,134,filed February 25, 1964. The synthesis of high silica-to-alumina ratioform of type Y zeolite using preferred proportions of the aforementionedreactants is claimed in our copending application Serial No. 397,277,filed September 17, 1964. The synthesis of faujasite from sodiumhydroxide solution and high temperature calcined clay per se is claimedin our copending application Serial No. 416,925, filed December 8, 1964.

FORMATION OF REACTION MASSES The solids should be minus 200 meshparticles, preferably finer, unless the material is in the form of apulverulent mass which will break down into minus 200 mesh particlesduring mixing. We may employ apparatus such as a pug mill to obtain thenecessary uniform mixture of ingredients. One method for forming ourmixture is to dry blend the sources of reactive silica and alumina, suchas a mixture of kaolin calcined below the exotherm and kaolin calcinedabove the exotherm, incorporate alkali solution at ambient temperatureand then adjust the mass to a consistency suitable for particleformation by addition of uncalcined clay. This mass can be reacted inbulk and subsequently granulated into particles of the desired form orshape. Preferably, however, we form our reaction mass into particles ofthe shape and form desired in the finished catalyst or contact masssince such form will be retained through processing. Inasmuch as ourreaction masses contain appreciable quantities of uncalcined kaolin claydiluent, these masses are readily amenable to particle formation bysimply forming means such as extrusion when we select a kaolin havinggood plasticity. In the absence of the uncalcined clay ingredient, thereactants required for sieve formation lack plasticity and thereforewould be extremely difficult to pelletize by extrusion or other formingmethod requiring the use of plastic mixtures. If desired, extruded greenpellets can be rounded by tumbling before they harden as a result ofchemical reaction. Particle forming methods other than extrusion can beused to form the agglomerates. As examples of other forming methods canbe mentioned molding, pilling and spray drying. It is also within thescope of the invention to agglomerate the solids on a rotating panv(e.g., a Dravo mill). For fluid bed operations /325 mesh particles areformed. For most moving bed catalyst operations, the particles should befrom about 4 to 8 mesh (Tyler).

REACTION The agglomerated reaction masses are reached under conditionsto prevent dehydration at suitable temperatures until the desiredsynthetic zeolite has formed. Suitable temperature or temperatures usedto react the ingredients and to form the desired zeolite will vary withthe ingredients, especially with the concentration and amount of sodiumoxide present. With some reaction mixtures it will be possible to heatthe freshly prepared masses to product temperatures within the range of150 F. to 200 F. under pressure sufiicient to prevent dehydration andmaintain the masses at temperatures with this range for a time up to 48hours or until the synthetic zeolite forms. Further heating of themasses under conditions to prevent dehydration will normally not bedetrimental. In the case, however, of reaction masses formulated withfairly dilute sodium hydroxide solutions, e.g., solutions having a NaOHconcentration of about 10 percent, the masses should be aged bymaintaining them at product temperatures with the range of about 70 F.to F. for at least about 4 hours, preferably 12 to 24 hours,

before heating the masses without dehydration at temperatures within therange of 150 F. to 200 F. for 12 to 48 hours, or until the zeoliteforms. Reaction masses formulated with sodium silicate as the source ofsodium oxide do not appear to be impaired by being heated immediately totemperatures of 150 F. to 200 F. under pressure sufficient to preventappreciable evaporation of water from the reactants.

The progress of the reaction can be followed by study ing the propertiesof the reactant masses. The presence of the desired molecular sieve canbe detected by adsorption studies or by catalytic evaluations onion-exchanged, activated samples. In many cases X-ray diffractionstudies can be used to detect the presence of a molecular sieve and alsoto estimate the quantity of sieve. X-ray patterns of the unactivatedreaction products will usually contain kaolinite peaks and also peakscharacteristic of crystalline impurities usually associated with kaolinclays.

As mentioned, reaction is carried out under conditions such as toprevent dehydration of the particles. Therefore, when heating thereaction masses the vapor pressure in the reaction vessel must be atleast as great as the vapor pressure generated by the reactants at theparticular heating temperature employed. The simplest methods forcarrying out the reaction utilize autogenous pressure. One method is tocarry out the reaction in an unvented heated vessel. Another means ofmaintaining the particles under substantially autogenous pressure whilethey are being heated is to immerse the particles in a nonreactive hydrocarbon oil heated to the desired temperature. Pressures substantiallygreater than autogenous can be used. The aging temperature, especiallythe initial aging temperature, may affect the species of zeolite thatcrystallizes from a given reaction mass. For example, either type Azeolite or faujasite type zeolites can be crystallized from certainreaction masses by controlling the temperature at which reaction isinitiated. When certain reaction masses are heated very rapidly toproduct temperatures above about 150 F. under autogenous pressure, typeA zeolite may be formed although the reaction masses are formulated witha sufficient quantity of a source of reactive silica to formfaujasite-type zeolites. By maintaining such masses at temperatures notappreciably exceeding 100 F. for several hours (e.g., 4 to 24 hours)before heating under autogenous pressure to temperatures of 150' to 200F. for 8 to 24 hours, a synthetic faujasite is formed.

To convert the hydrous products into active contact masses, themolecular sieve portion of the products must be at least partiallydehydrated by calcination at temperatures within the range of about 600F. to 1400 F. and for times within the range of /2 to 24 hours. When theactive contact mass is a cracking catalyst, the clay diluent as well asthe zeolite should be dehydrated. The crystallized products can beion-exchanged before or after the calcination, preferably beforecalcination. To produce catalysts, it may be desirable to exchange asubstantial amount of the alkali metal ions of the zeolite. In producingcatalysts, the following ionizable compounds can be used to replace thealkali metal of the zeolite: salts of barium, calcium, magnesium,manganese, vanadium, chromium, cerium, cobalt, nickel, iron, zinc,aluminum, rare earths (lanthanum, praesodymium, neodymium and samarium),hydrogen, ammonium and mixtures of the foregoing. The salts can beinorganic, such as the chloride, or organic, such as the acetate.Normally, the ionizable salt will be used in the form of an aqueoussolution. Conditions for base-exchanging alkali metal aluminosilicates,especially alkali metal aluminosilicates of the molecular sieve type,are well known. Known conditions of time and temperature can be used incarrying out the ion-exchange. To activate the ion-exchangedagglomerates and produce a catalyst, the agglomerates are calcined inair at temperatures usually within the range of about 900 F. to 1100 F.and for times within the range of /2 to 24 hours. The activation can becarried out in a cracking unit of a refinery or the particles can beactivated before use in the cracking unit. It may be desirable to givethe catalyst a finishing treatment by heating the catalyst particles inthe presence of steam to a temperature within the range of 10 00 F. to1500 F. to adjust the activity to a desired level. Steaming at 1000 F.to 1450 F. with 100 percent steam for 1 to 4 hours is especiallyrecommended for such activity adjustment.

As mentioned, we preferably ion-exchange the reacted masses beforethermal treatment and subsequently deiydrate the ion-exchanged masses bycalcination. Using this sequence, substantially all of the alkali in theparticles, including the alkali associated with the uncalcined kaolinclay, can be exchanged. A typical calcium-exchanged catalyst obtained inthis manner and formulated to contain about 10 percent type Y sievecontained about 7 percent by weight (3210 and appreciably less than 1percent Na O. When a similar reaction mass was dehydrated beforeexchanging with calcium ions, a catalyst containing about 5 percent Na Oand 2 percent CaO was obtained. The latter catalyst was poor in activityand in steam stability, as compared to the catalyst in which exchangewas carried out before dehydration.

Catalysts of the present invention containing faujasitetype molecularsieves are useful for cracking hydrocarbon oils of the type used ascatalytic cracking feedstocks. The cracking operation can be carried outat catalyst temperatures of about 800 F. to about 1000 F. with pressuresfrom 1 to 4 atmospheres (absolute). These catalysts are especiallyuseful in cracking to high conversion levels, i.e., conversion levelsabove about 55 percent. The cat alysts of this invention are highlyselective, even at exceptionally high conversion levels. This fact isevident rom the exceptionally high gasoline yields and desirably lowcoke and gas yields. Coke yield is usually appreciably less than that ofcommercial kaolin catalyst at the same conversion.

The following examples are given to illustrate this invention andcertain features thereof.

The following kaolin clays were used in the preparalions described inthe examples.

Physical Characteristics Satiutonc #1 Satiutone #2 ASP 200 SpecificGravity 2 03 2.50 2.58 Moisture, Maximum Wt.

percent 1 0 1.0 1.0 Wt. perccnt+325 mesh (wet screen) 0.5 0.5 0.01Average Particle Size, Mi-

crons 2.0 4. 5 0.55 p. 5.8-6.3 5.8-6.3 3.8-5.0 Typical ysis(Moisture-free Weight Basis): Ignition Loss at 1 800 F.,

cent 2. 0 2.0 1. 5 calcination. Treatment. 1 Caleiued 2 CalcinedUncalcincd Composition I. Whiteness (G.E.), percent...

Amorphous 4 Amorphous 5 Crystalline Above exotherm.

2 Below exotherm.

3 Possibly incipient luullite.

' Metakaolin.

5 Kaolinite.

The Edgar Plastic Kaolin and Putnam clay used in some of the examplesare similar to ASP 200 but are somewhat finer in article size andpossess greater plasticity. These clays are described in US. 2,489,332to Hubert A. Shabaker. Min-Chem Special clay is similar to ASP 200 inchemical composition but has an average particle size of about 3.5microns.

The hardness of catalyst pellets produced in accordance with thisinvention was measured by the so-called 4-ball hardness test, a testwidely employed in evaluating the resistance of catalyst particles tophysical disintegration when subjected to the action of very strongattritive forces. In carrying out the hardness tests, plus mesh (Tyler)test sample previously calcined at 1050 F. and stored in a desiccatorwas poured into a tared 100 cc. graduate cylinder to the 80 cc. mark,with gentle tapping to pack the particles and the weight of 800 cc. ofthe sample determined. 80 cc. of sample was placed into a stainlesssteel cylindrical container with four polished stainless steel ballbearings, each of V diameter. The container was closed tightly and itwas then rotated about its longitudinal axis on a roller arrangement atabout 80 rpm. for one hour. After rotation had ceased, the particles inthe container were screened on a limiting sieve (a 6 mesh sieve) and thehardness calculated as the percentage of total sample weight representedby the fraction of the material retained on the limiting sieve.

Catalytic data mentioned herein were obtained in a cracking test unitdesigned to evaluate the activity of a cracking catalyst at standardconditions. This test, referred to as the CAT-D test, is a modificationof the CAT-A method described in Laboratory Method for Determining theActivity of Cracking Catalysts, by J. Alexander and H. E. Shimp, pageR537, National Petroleum News, Aug. 2, 1944. In carrying out the CAT-Dtest a heavy gas oil feedstock is used and cracking is carried out at900 F. with 10 percent steam and a liquid space rate of 1.0 (volumecharge/volume of catalyst/ hour) for a minute operation period.

The term kaolin coke factor used in presenting comparative catalyticdata refers to a value obtained by comparing coke made of theexperimental catalyst to that of commercial kaolin catalyst at the sameconversion (extrapolated.)

The commercial catalyst was obtained by reacting kaolin clay withsulfuric acid followed by reductive desulfation. The commercial catalystcontained about 45 percent A1 0 the balance being substantially SiO AllX-ray diffraction data referred to in these examples Were obtained fromrandom powder patterns using the K-alpha doublet of copper as the sourceof X-radiation, a receiving slit width of 0.006, a Norelco specimenholder having a sample area of 0.812" x 0.408", a 3 take-off angle, ascintillation counter, a scanning rate of 2 per minute, a time constantof 4 seconds, a scanning direction increasing from 2 to 90, and a stripchart pen recorder. Specimens were equilibrated at 25 C. and 40 percentto 50 percent relative humidity for at least 18 hours prior to X-raying.Peak heights (counts per second, or c./s.") and positions were recordedon the strip chart.

In view of the similarity between the diffraction patterns of the X andY molecular sieves, each of which has a characteristic maximum at 6.22.9, the X zeolite was distinguished from Y zeolite by applying to X-raypowder diffraction patterns of products the criterion set forth in TableIII of a publication by Donald C. Freeman, In, entitled ElectricalConductivity of Synthetic Crystalline Zeolites, Journal of ChemicalPhysics, vol. 35 No. 3, September 1961. Table III in said publicationcorrelates unit cell dimension with SiO /Al O ratio. To make adetermination as to zeolite identity, the peak located at about 31 20 onthe powder diffraction pattern of a sample was observed. If such peakwas located below 31.12" 20, corresponding to a SiO /Al O ratio of 3.00as shown in Table III of the publication, the zeolite was identified asX. If the peak at about 31 26 was located at or above 3l.l3 26, thezeolite was identified as Y.

In estimating percent crystalline zeolite of products, a commercialsample of type 13X zeolite was used as a reference. This sample, assumedto contain 100 percent zeolite, had a 62 20 peak height of 880 c./s.Percent sieve in samples was estimated by observing the intensity of the6.2 20 peak in c./s. and multiplying such value by the factor 100/880.

Example I This example illustrates the preparation, in accordance withour invention, of a highly selective and active cracking catalystcontaining the calcium form of type X synthetic zeolite in the presenceof dehydrated kaolin diluent.

A reaction mass was obtained by forming a uniform mixture of thefollowing ingredients:

Component: Grams Satintone #1 126.0 Satintone #2 333.0

Edgar Plastic Kaolin 1430.0 26% aqueous NaOH solution (density 1.28)688.6

Initially the two Satintones were dry blended and then mixed with sodiumhydroxide solution in a worm-type pug mill. The sodium hydroxidesolution was at room temperature when it was incorporated with thecalcined clays. The plastic kaolin was added to the mixture of calcinedclay and alkali solution. Total pugging time was about 50 minutes. Themixture was then extruded in a piston-type extruder having 0.17"diameter holes. The extrudate was cut into pellets about 0.25 long asthey issued from the extruder. The pellets were immersed in acirculating bath of white mineral oil and maintained there for 24 hours.The oil temperature was maintained at F. during this time. The pelletswere then placed in a jar and covered with some of the hot white mineraloil. The jar was sealed and held in a 200 F. oven for 24 hours tocrystallize the zeolite.

An X-ray diffraction pattern of the aged pellets indicated that type Xzeolite was the only crystalline zeolite present. Kaolinite was alsopresent as a crystalline phase, as was expected. The height of thecharacteristic faujasite peak at 6.2 20 was 96 c./s. From this data itwas estimated that the pellets contained about 11 percent type X zeolite(hydrated sodium form), the balance being kaolinite and an amorphousaluminum silicate phase derived from the calcined clay.

This intermediate was then washed by percolation with 4825 ml. of waterat room temperature, producing an efiluent having a pH of 10.8. Thewashed pellets were base exchanged with 1.06 N calcium chloride solutionby percolating 6400 ml. of the exchanging solution through the pelletsat 180 F. The pellets were then Washed with 3000 ml. of distilled waterat room temperature and dried at 200 F. for two hours. The L.O.I. of theproduct was 19.09 percent. An X-ray diflfraction indicated that theproduct contained a mixture of type X zeolite and kaolinite.

To convert the pellets into an active cracking catalyst, the pelletswere calcined in air in a muflle furnace at 1050 F. for three hours. Achemical analysis of the calcined catalyst product indicated it had thefollowing composition:

Volatile free basis,

weight percent CaO 6.75 Na O 0.19 Al O 42.8 SiO 50.3

Calculated from analyses of clay reactants.

favorably with the commercial 4-ball hardness of some commercialcracking catalysts.

Catalyst density was 0.92 g./ cc.

The catalyst was steamed at 1350 F. for four hours, using 100 percentsteam and evaluated for cracking properties. A comparison of theintensity of the 62 26 line of the pellets before and after the steamstabilization treatment indicated that the steaming destroyed about halfof the crystal structure of the Zeolite and it was estimated that thesteamed catalyst contained about percent crystalline molecular sieve(type X).

The CAT-D properties of the experimental catalyst and a sample of thecommercial kaolin cracking catalyst were compared. The results of thecomparison are summarized in Table I.

TABLE 1 [Catalytic evaluations (CAT-D Test) of catalysts derived fromkaolin clay] Experimental Commercial Kaolin Catalyst Kaolin CatalystData in Table I show that under identical test conditions theexperimental kaolin catalyst was considerably more efficient as acracking catalyst than the commercial acidactivated kaolin catalyst(68.7 percent efiiciency for the experimental catalyst as compared withonly 59.0 Percent efficiency for the commercial catalyst). Theexperimental catalyst converted 67.8 percent of the feedstock, producinga 53.0 percent gasoline yield. The low Kaolin Coke Factor of theexperimental catalyst is a further indication of its outstandingselectivity. Another desirable feature of the experimental catalyst wasthat the gas product had a very high specific gravity, indicating that Cand C olefins were produced instead of hydrogen, which would havereduced gas gravity.

Example II Component: Parts by weight Satintone #1 237 Satintone #2 222ASP 200 1160 18.7% NaOH solution 643 Mixing was in a water cooled pugmill and was carried out by dry blending the calcined kaolines, as inExample I, adding NaOH solution (at room temperature) and thenuncalcined clay. Extrusion was in the piston extruder. The pellets wereaged for 24 hours by immersing them in mineral oil maintained at 100 F.The pellets and some of the hot oil were transferred to a glass jar andthe jar was sealed. The sealed jar with the pellets was held in a 200 F.oven for 24 hours to crystallize the zeolite.

The pellets were then washed, exchanged with 1.06 N calcium chloridesolution and rewashed, as in the previous example. The exchanged pelletswere then dried at 200 F. for 3 hours, calcined at 1050 F. in a mutfiefurnace for 3 hours and steamed at 1350 F. for 3 hours with 100 percentsteam. I

16 An X-ray pattern studied in conjunction with the article in Journalof Chemical Physics showed that in addition to a small amount ofresidual kaolinite the only crystalline phase present was type Yzeolite.

Data for the catalytic properties of the pellets are summarized in TableII.

Table IL-Catalyiic evaluation of experimental catalyst Gasoline, vol.percent 57.9 Coke, wt. percent 3.1 Gas, wt. percent 16.9 Conversion, wt.percent 71.0 Gas gravity (air=1.0) 1.53 Kaolin coke factor 0.37 Crackingefiiciency, wt. percent 71.8

These data show that the calcium-sieve composite was an extremely activeand selective catalyst.

The catalyst was then steamed at 1400 F. for 3 hours and retested by theCAT-D test. The catalyst was found to be substantially unchanged inactivity and selectivity, indicating that it was still stable after the1400 F. steam treatment.

Example III Still in accordance with this invention, a molecular sievetype cracking catalyst of outstanding steam stability was formed bycrystallizing type Y zeolite from reactants including sodiummetasilicate solution, metakaolin and uncalcined kaolin clay.

An 18 percent aqueous solution of Na SiO was prepared by heating 502.0grams Na SiO .9H O in 698 ml. distilled water and mixing until thesodium silicate had dissolved. The solution was permitted to cool toroom temperature. Satintone #2 was mixed thoroughly in a pug mill withthis cooled solution, using 90.0 grams of Satintone #2 and 822.0 gramsof the 18 percent sodium silicate solution. 1800.0 grams of ASP 200 wasthen pugged into the mixture. Total pugging time was 40 minutes. Themixture was then extruded in a piston extruder having 0.17" diameteropenings. The extrudate was cut into pellets about 0.25 long as theyissued from the extruder.

(a) A portion of the pellets was immersed in a circulating bath of whitemineral oil maintained at F. Pellet retention time was 24 hours. Thepellets were placed in a glass jar, covered with some of the hot oil andthe jar sealed. The jar was placed in a 200 F. oven and maintained inthe oven for 24 hours. Oil was drained from the reacted pellets and theywere washed with distilled water at room temperature until the pH of theeflluent was 10.9. The pellets were then exchanged at 180 F.il0 F. with1.06 N CaCl solution until the aqueous efiluent had a Na O content of0.03 g./100 ml. The exchanged pellets were then washed with distilledwater until the effluent was chloride-free. The pellets were dried at300 F. and calcined at 1050 F. in a muffle furnace for 3 hours. Achemical analysis of the product indicated that it contained 0.24percent Na O, 2.98 percent C210 and 16.0 percent L.O.I. From the factthat the 62 20 peak on the X-ray pattern had an intensity of 51 c./s.,it was estimated that the catalyst contained 5.8 percent crystallinetype Y zeolite.

The exchanged pellets were steamed at 1350 F. for 4 hours with 100percent steam. A CAT-D test was run on the steamed pellets. To evaluatestability of the pellets, the pellets were steamed at 1400 F. for 4hours and another CAT-D test was made. This procedure was repeated withsteam treatments at 1400 F, 1450 F., and 1500 F., each steam treatmentbeing for 4 hours with 100 percent steam. Results tabulated in Table IIIshow that the material was a very active and selective cracking catalysteven after the 1500 F. steam treatment.

TABLE III [Stability of experimental catalyst] Steam Treatment, F./4 hr1,350 1, 400

CAT-D Properties:

Gasoline, vol. percent Coke, wt. percent Gas, wt. percent Conversion,wt. percent Gas Gravity (Air= 1.0) Kaolin Coke Factor..- CrackingEfliciency once This example illustrates the preparation of a highsilica content catalyst of excellent thermal and steam stability inaccordance with this invention.

The procedure of Example I was repeated with the following reactionmixture:

Parts by wt. Satintone #1 340 Satintone #2 133 ASP 200 1160 16.8%aqueous NaOH solution 635 The reaction mixture was pugged, extruded, oilaged at 100 F. and then crystallized at 200 F. in a sealed jar, as inExample I, producing a mixture of type Y Zeolite and kaolinite. Aportion of the pellets was dried at 200 F. for three hours. Theuncalcined pellets were ion-exchanged with calcium as in Example I andthen steamed at 1350 F. with 100 percent steam to adjust the activity.X-ray data indicated that the preparation had a 6.2 20 peak height of 58c./s., indicating that it contained 7 percent crystalline zeolite. Thepeak at about 31 20 indicated that the zeolite was type Y.

A CAT-D test was run on the pellets after 1350 F. steaming. Thesepellets were then steamed at 1400 F. for four hours with 100 percentsteam and another CAT-D test run. The procedure was repeated with steamat 1450 F., 1500 F., 1550 F. and 1600 -F. The results are given in TableIV.

TABLE IV [Stability of experimental catalysts] Data in Table -IV showthat the preparation was an extremely active cracking catalyst. The 46.4percent conversion figure for the catalyst after 1550 F. steamingindicates that the catalyst was still very active after such steamtreatment.

A sample of the catalyst after the catalytic evaluation at 1550 F. had a4-ball hardness of 95.8 percent.

Example V This example illustrates the preparation, also in accordancewith this invention, of improved type A molecular sieve adsorbents.

Metakaolin was produced by calcining water-washed Georgia kaolin clay ina muffle furnace at 1300 F. for four hours. The clay was a fine sizefraction of clay having at least 92 percent by weight of the particlesfiner than 2 microns (as determined by the Casagrande method). Eighthundred and fifty grams of the calcined clay was mixed with 17 0 gramsof Edgar Plastic Kaolin clay in a screw-type pug mill. The clays wereblended for about 10 minutes and then 752 grams of a 41.9 percentsolution of sodium hydroxide in water was added. The mixture was puggedfor about 20 minutes. Fortyfive milliliters of distilled water was thenadded to bring the mixture to an extrudable consistency and the chargein the pug mill was pugged for an additional 10 minutes. The mixture wasextruded through a die plate under a pressure of 9 to 10 tons intopellets: about As-inch diameter.

A portion of the fresh pellets was placed directly in a circulating bathof hydrocarbon oil maintained at 160 F. The pellets were kept in theheated oil for 24 hours. The pellets were placed in a jar and coveredwith some of the 160 F. hydrocarbon oil. The jar with pellets and oilwas sealed tightly and placed in an oven maintained at 200 F. The jarwas held in the 200 F. oven for 66 hours. From X-ray data it wasestimated that the product contained 64 percent crystalline 4A zeolite.Characteristic kaolinite peaks were not present in the X-ray pattern,indicating that the kaolinite structure had been destroyed during thereaction.

One portion of the pellets was activated by heating in air at 200 F. forthree hours. Another portion was activated by heating in a niufllefurnace at 1050 F. for onehalf hour. The activated samples werepermitted to cool in sealed jars and then tested for resistance toslaking by immersing the pellets in distilled Water at room temperature75 F. and observing the pellets immediately and after 24 hours. It wasfound that the pellets treated at 200 F. and 1050 F. were substantiallyunchanged even after being immersed for 24 hours and substantially nopowder appeared in the Water, indicating that the activated pellets werewater stable and did not break down.

' Example VI Pelleted catalyst composites containing a mixture of azeolite having substantially the X-ray diffraction pattern of type Yzeolite and calcined kaolin clay were obtained by two procedures.

The first procedure was carried out in accordance with the presentinvention. 3887 grams of Satintone #1 and 648 grams Satintone #2 weremixed with 4000 ml. of 16 percent sodium hydroxide solution. 9085 gramsof a coarse size fraction of high purity raw Georgia kaolin (Min-ChemSpecial) was added, followed by an additional 850 ml. of the 16 percentcaustic solution. The mixture was pugged and extruded. The extrudate wasmaintained in sealed jars at room temperature of about 75 F. for 24hours and in a 200 F. oven for 24 hours. The pellets were exchanged with1.0 N ammonium nitrate solution to a Na O content below 0.78 percent(based on the volatile free pellet weight) and then steam stabilized forfour hours with percent steam. The product was an active catalyst havinga ball mill hardness of 97.7.

In the second procedure, carried out under conditions outside the scopeof this invention, type: Y zeolite was crystallized, pulverized,pelletized by mixing with water and plastic clay and then steamed. Thedetails of the second procedure are as follows:

666 grams of Satintone #2 was mixed with 600 ml. of a 20 percent(wt/vol.) aqueous solution of sodium hydroxide in a large stainlesssteel beaker with a prop ellor-type mixer until the mixture was smooth.Then an additional 1800 ml. of the caustic solution and 1998 grams ofSatintone #1 were alternately added over a period of an hour. Mixing wascontinued for about hour, at the end of which time the slurry was quitesolid as compared with the original mixture. The mixture was aged in acovered container at room temperature (about 70 F.) and then at 200 F.for 70 hours, resulting in the crystallization of sodium zeolite Y. Thezeolite sample was washed until the pH of the effluent was less than 12and then exchanged with a 1.0 N aqueous solution of ammonium chloride ina batch exchange process. The exchange was carried out until the Na+concentration of the eiliuent was less than 0.05 percent, as determinedby a sodium specificelectrode. The product was then washed on a Buchnerfunnel with distilled water to remove excess chloride ion. The washedion-exchanged zeolite was air dried, passed through an 8-mesh screen tobreak up the dried zeolite and then micropulverized with a 0.020"screen. An X-ray analysis of the product indicated that the productcontained about 70 percent zeolite and having a SiO /Al O mol ratio of4.08 to 1.

The analysis of sample was as follows:

L.O.I. 25.88 Percent Na O 2.63 Percent CaO 0.47 Percent NH; 3.80

Using a small worm pug mill provided with a water jacket for cooling,242 grams of the zeolite composition was blended for five minutes with1170 grams of Edgar Plastic Kaolin clay. Distilled water was slowlyadded in increments of 25 ml. until a total of 400 ml. was added, Thetotal pugging time was about 45 minutes. Using a piston extruder, 1. /2tons of 4" ram, the mixture was extruded into strands about 0.17"diameter. These strands were cut into pellets about 0.17" long. Thepellets were placed in a porcelain pan and dried in an oven at 250 F.for 24 hours.

Four-ball catalyst pellet hardness tests were made of each catalystafter catalytic evaluation and the steaming at 1550 F. for four hours.The hardness of the catalyst produced by following the process of theinvention was 95.8 percent. The hardness values of the pellets made bythe second procedure, outside the scope of this invention, was only 72.2percent. 1

Example VII This example illustrates the preparation of a crackingcatalyst from a single calcined kaolin clay, sodium hydroxide solutionand a coarse size fraction of raw high purity kaolin (Min-Chem Special).

Twelve and one-tenth pounds of Satintone #1 was slowly mixed in a panwith 11.0 pounds of 16.0 percent NaOH solution (weight basis). Themixing was carried out with a glass rod and was continued until themixture had an apparently uniform consistency. Min- Chem Special wascharged to a double-screw pug mill in amount of 20.0 pounds. To thecharge in the pug mill, the mixture of calcined kaolin clay and alkalisolution was added. One and five-tenths pounds of 16 percent NaOHsolution was used to rinse the pan that contained the slurry and, afterbeing used to rinse out the pan, the caustic was added to the pug mill.

The batch was pugged for minutes after the final addition of causticsolution. The temperature of the charge in the pugger was about 90 F. atthe end of the pugging. The mixture was extruded under vacuum in aworm-type extruder having 0.17" diameter holes and the extrudate was cutinto pellets about 0.25" long as they issued from the extruder. Theextrusion was made while the charge in the extruder was under vacuum.The extrudate temperature increased gradually from 100 F. at thebeginning of the extrusion to 127 F. after 21 minutes when the extrusionwas completed.

The freshly extruded pellets were placed in half gallon glass jars withthe pellets substantially filling the jars.

20 The jars were sealed tightly and maintained at room temperature ofabout F. for 48 hours. The jars with contents were then placed in anoven maintained at 200 F. and held in the oven for a 72 hour period.

Without being washed or dried, 800 to 900 gram batches of the pelletswere exchanged at 180 R110 F. with 1 N ammonium nitrate solution bycontinuous percolation of the solution through batches of the pellets inexchange columns for about 48 hours. At the end of the exchanges, the NaO content of the efiluents were typically less than about 0.05 g./ ml.(as determined with a pH meter using a sodium-specific electrode). ThepH of the etlluents was about 7.3.

The exchanged pellets were steam stabilized in a tube furnace at 1563 F.for four hours with 100 percent steam. After the steam treatment, themost significant physical properties of the catalyst were determined andcatalytic properties were evaluated by the CAT-D method. The results arereported in Table V.

Table V.-Pr0perties of experimental catalyst Vol. percent gasoline 48.5Wt. percent coke 2.3 Wt. percent gas 13.3 Gas gravity (air=1.0) 1.36 Wt.percent conversion 56.2 Kaolin coke factor 0.55 Ball mill hardness 96.2

We claim:

1. A method for producing a composite base material adapted for use inthe preparation of an active contact mass which comprises forming areaction mixture comprising water, a source of reactive silica, a sourceof reactive alumina, a water-soluble source of an alkali metal oxide andfinely divided hydrated kaolin clay, said water and said sources ofsilica, alumina and alkali metal oxide being such as to form a slurry inthe absence of said hydrated kaolin clay and said hydrated kaolin claybeing present in quantity to form coherent particles when present withsaid other ingredients, said sources of silica, alumina and alkali metaloxide being present in amount such that when said particles aresubjected to hydrothermal treatment without dehydration, a crystallinezeolite molecular sieve is formed,

forming said mixture into coherent particles,

and subjecting said particles to hydrothermal treatment until asynthetic molecular sieve zeolite crystallizes, thereby forming stronglybonded particles comprising a mixture of kaolin clay and crystallinezeolitic molecular sieve.

2. The method of claim 1 wherein said particles comprising kaolin clayand crystallize zeolite are ion-exchanged with nonalkali-metal cationsand dehydrated to produce a composite catalyst.

3. The method of claim 1 wherein said source of reactive alumina is afinely divided mineral which contains alumina and said source ofreactive silica is a finely divided mineral which contains silica andsodium hy' droxide is a source of said alkali metal oxide and isemployed in amount such that the sodium hydroxide concentration in saidcoherent particles is within the range of 10 percent to 35 percent byweight.

4. The method of claim 3 wherein finely divided sub-' stantiallyanhydrous amorphous calcined kaolin clay comprises said source of silicaand said source of alumina.

5. The method of claim 4 wherein said calcined kaolin clay includes claythat has been calcined at a temperature and for a time such that thekaolinite exotherm has taken place after dehydration is completed.

6. The method of claim 1 wherein the synthetic crystalline zeolite thatcrystallizes by hydrothermal treatment of said particles is selectedfrom the group consisting of sodium zeolite X and sodium zeolite Y, andsaid reaction mixture comprises an aqueous sodium hydroxide solution of10 percent to 20 percent concentration, to 100 parts by weight ofcalcined kaolin clay including amorphous particles of kaolin clay thathave been calcined under conditions of temperature and time such thatthe kaolin exotherm has taken place after dehydration is completed, anduncalcined kaolin clay in amount of at least 100 parts by weight andsufiicient to form coherent particles with said calcined kaolin clay andsodium hydroxide solution.

7. The method of claim 1 wherein the synthetic crystalline zeolite thatcrystallizes by hydrothermal treatment of said particles has the X-raydiffraction pattern corresponding substantially to that of sodiumzeolite Y, and said reaction mixture comprises: an aqueous sodiumhydroxide solution of percent to percent concentration, 1 mol ofmetakaolin with from 3 to 7 mols of kaolin clay that has been calcinedunder COnClitiOns of temperature and time such that the kaolin exothermhas taken place after dehydration is completed, and uncalcined kaolinclay in amount at least equal to the weight of the metakaolin and saidother calcined clay and sufiicient to form a plastic mixture.

8. The method of claim 7 wherein said mixture is re acted underhydrothermal conditions at a temperature below 130 F. before beingcrystallized hydrothermally at a more elevated temperature.

9. The method of claim 1 wherein the synthetic crystalline zeolite thatcrystallizes by hydrothermal treatment of said particles is selectedfrom the group consisting of sodium zeolite X and sodium zeolite Y, andsaid reaction mixture comprises metakaolin, sodium silicate solution anduncalcined kaolin clay.

10. The method of claim 1 wherein the synthetic crystalline zeolite thatcrystallizes by hydrothermal treatment of said particles is sodiumzeolite A and said reaction is composed of metakaolin, aqueous sodiumhydroxide of 30 percent to 45 percent concentration and uncalcinedkaolin clay.

11. In a method for making a composite zeolite-type catalyst, the stepsof preparing a mixture comprising: calcined kaolin clay includingmetakaolin and amorphous dehydrated kaolin clay that has been calcinedat a temperature and for a time such that the kaolin exotherm has takenplace after dehydration, sodium hydroxide in the form of an aqueoussolution, and uncalcined kaolin clay in amount sufiicient to preservethe particulate nature of the mixture after the mixture has been shapedinto particles, shaping the mixture into particles, and crystallizingsaid mixture under conditions of pressure and temperature to preventdehydration, thereby producing particles which, when base exchanged withnonalkali-metal cations and dehydrated, constitute an active crackingcatalyst.

12. The method of claim 11 wherein said mixture comprises:

(l) Substantially completely dehydrated kaolin clay obtained bycalcination at temperature below which the kaolin exotherm takes place,1 mol;

(2) Substantially completely dehydrated kaolin clay obtained bycalcination at temperature above which kaolin exotherm takes place, /2to 10 mols;

(3) Fully hydrated uncalcined kaolin clay, at least combined amount of(1) and (2) on a weight basis;

(4) Sodium hydroxide solution of 10 percent to 30 percent concentration,to supply 0.45 to 1.2 mols Na O per mol A1 0 in (1) and (2);

and sodium cations in said particles are exchanged with nonalkali-metalions.

13. A method for making hard and porous catalyst pellets containingsynthetic faujas'ite which comprises forming a uniform mixture of thefollowing materials:

(1) metakaolin, 1 mol;

(2) fully hydrated uncalcined kaolin clay, I to 30 mols;

(3) aqueous solution of sodium silicate, to supply 1 mol Na O plus 0.05to 0.80 mols Na O per mol (2) and 0.5 to 3.5 mols SiO pelletizing saidmixture, heating said pellets at a temperature within the range of about150 F. to about 200 F. under pressure sufiicient to prevent dehydrationuntil synthetic faujasite is formed, exchanging sodium cations in saidpellets with nonalkali-metal ions and activating said pellets bycalcining them at a temperature and for a time sufficient to dehydratesaid hydrated kaolin clay.

14. A method for producing mechanically strong particles composed of amixture of zeolitic molecular sieve crystals and hydrated kaolin claycrystals which comprises forming particles comprising a mixture ofhydrated crystalline kaolin clay, water and sources of alkali metaloxide, silica and alumina, said sources being present in relativeproportions to form a crystalline zeolitic molecular sieve when saidparticles are subjected to hydrothermal treatment without dehydration.

while said kaolin clay in said particles is still hydrated,

heating said particles in the absence of an external aqueous phase underconditions of temperature and pressure suflicient to prevent dehydrationuntil a zeolitic molecular sieve crystallizes, thereby forming particlescomposed of a mixture of zeolitic molecular sieve crystals and kaolinclay crystals.

15. The method of claim 14 wherein said heating step is carried out bymaintaining said particles at a temperature within the range of 70 F. toF. for at least 4 hours and then heating them at a temperature withinthe range of F. to 200 F. until said zeolite crystallizes.

16. The method of claim 15 in which said particles are immersed in oilwhen maintained at said temperature within the range of 70 F. to 130 F.and when heated at said temperature within the range of 150 F. to 200 F.

17. A method for making a composite catalyst which comprises: forming amixture comprising sodium hydroxide solution of 10% to 20%concentration, 1 mol metakaolin, 3 to 7 mols of kaolin clay that hasbeen calcined under conditions of temperature and time such that thekaolin exotherm has taken place after dehydration is completed,uncalcined kaolin in amount at least equal to the weight of themetakaolin and said other calcined kaolin clay and sufficient to form aplastic mixture, the Na O oxide in said sodium hydroxide solution beingpresent in amount within the range of 0.50 to 0.75 mols per mol total A10 in said metakaolin and said other calcined kaolin clay,

extruding the mixture to form pellets,

immersing the pellets in oil,

heating the pellets While they are immersed in the oil under pressuresufiicient to prevent dehydration until a zeolite having substantiallythe X-ray diffraction pattern of sodium zeolite Y crystallizes andcrystalline kaolin clay is also still present,

separating the pellets from the oil,

ion-exchanging the pellets to exchange sodium ions with nonalkali-metalcations,

and thermally activating the ion-exchanged pellets.

18. The method of claim 17 wherein said pellets are exchanged withammonium ion.

References Cited UNITED STATES PATENTS 2,973,327 2/1961 Mitchell et a1.252449 3,119,659 1/1964 Taggart et al 23-112 3,205,037 9/1965 Maher eta1 23--1l2 3,224,643 4/1966 Schwartz 252-455 DANIEL E. WYMAN, PrimaryExaminer.

C. F. DEES, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,367,886 February 6, 1968 Walter L. Haden, Jr., et al.

It is hereby certified that error appears in the above numbered pat entrequiring correction and that the said Letters Patent should read ascorrected below.

Column 9, line 28, for "A1 O .2SiO]' read Al O .2SiO2) column 13, line33, for "coke made of read coke make of line 50, for "c./s." read"c./s." column 15, line 61, for "calcined kaolines" read calcinedkaolins Signed and sealed this 22nd day of April 1969.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer

